The invention is particularly adapted to scissors which are economical to manufacture and assemble into a completely operable unit without overriding or overrunning of the material trapped between the blades. One specific use for such scissors is as disposable suture scissors, often desired by a physician because they are ready for use without necessity for fresh sterilization and they will cut cleanly at the very tip of the cutting edges, yet are sufficiently economical to be disposable without the necessity for subsequent cleaning and sterilization before reuse.
It has been necessary to sterilize surgical instruments in hospitals and doctors' offices, and this has become increasingly costly in both time and personnel involved. Accordingly, this has emphasized the great desirability for surgical instruments that may be sterilized at the plant of the manufacturer and sterile-packaged, and which may then be removed from the sterile package, used, and disposed of immediately after use. This eliminates the clean-up and subsequent sterilization, and also eliminates the delay for sterilizing the instrument before it may be used.
The prior art has known a previous attempt to make a disposable suture cutter, as set forth in U.S. Pat. No. 3,003,236. Such suture cutter was formed from a single strip of stainless steel, bent and twisted, and interengaged at a unitary pivot so as to act as a cutter. Due to the construction, which included the single strip of metal which formed the cutter and interconnected handles, the cutter was continuously biased open so that there was no protection for the cutting edges. Also, the unitary pivot strut from the metal of one blade established a poor pivot connection, with inherent lost motion. The cutter was provided with a stop, but it was a piece of metal bent from one edge of one blade and disposed at about a 45-degree angle to the plane of the blade so that there was a sharp edge on the stop extending beyond the thickness of the cutter, which could scratch a person on which the sutures were being cut, and also, due to the angular disposition of the stop, the handles could be latched closed. Further, due to the angular disposition of the stop, the blades could be forced together at the rear of the pivot, which would tend to separate the blades transversely at the cutting edges, impairing the cutting action.
A still further objection is that, due to the one-piece construction, the handles were normally disposed in a condition in which the cutting edges were biased open so that there was no protection for the cutting edges. Then, in order to utilize the cutter, the operator had to squeeze the handles together, and the more they were squeezed together, the more force was required to overcome the inherent spring bias of such handles. This relatively high closing force meant that once the stop was engaged, the operator could hardly tell that such stop had been engaged because there was little added resistance to movement of the handles, and hence the operator tended to overclose the handles because there was not a good "feel" or tactile sensation of the stop means actually interengaging.
The problem to be solved, therefore, is how to construct scissors which may be economically manufactured and assembled for proper operation, wherein the scissors may have a properly positioned stop for preventing overclosing of the cutting edges, with the stop having a positive action which is cushioned.